Rotary impact drilling tool



May 12, 1964 w. T. SCHRUM, sR., ETAL ,7

ROTARY IMPACT DRILLING TOOL Filed Sept. 29, 1960 s Sheets-Sheet 1 INVENTOR. A 33 w/wup r. SCWPUM, s2

42 W/LL/AM E. 7PZ/XAL May 12 1964 w. T. SCHRUM, SR; ETAL 3,132,702

ROTARY IMPACT DRILLING TOOL Filed Sept. 29, 1960 3 Sheets-Sheet 2 INVENTOR. W/LBUP 7. \SCHPUMSR.

May 12, 1964 w. T. SCHRUM, sR.. ETAL 3,132,702

ROTARY IMPACT DRILLING TOOL Filed Sept. 29, 1960 3 Sheets-Sheet 3 United States Patent 3,132,702 ROTARY REACT DRILLING TGGL Wilbur T. Schrum, Sn, Latrobe, and William E. Truxal, Youngwood, Pa, assignors to Impact Rotor Tool Ina, Latrobe, Fa, a corporation of Pennsylvania Filed Sept. 29, 19%, Ser. No. 59,235 10 Claims. ((11. 173-57) This invention relates to a rotary impact drilling tool useful for boring holes in or coring of relatively hard materials such as rock. More particularly, this invention relates to such a tool useful in underground mines for drilling of bolt holes for roof bolts, holes for explosives, in rock quarries, for road construction and other uses where the material to be drilled is relatively hard and may or may not be uniform.

In recent years, it has become a common practice to hold up the roof in underground coal mines, for example, by means of roof bolts. The holes for such bolts have heretofore been drilled by a pneumatic jack hammer, or by a rotary drill preferably operated by a power-driven roof bolt hole boring machine. Following the withdrawal of the boring drill, a roof bolt usually with an expansion member is put in each hole and tightened by a wrench to secure the bolt in place and hold the roof against falling. Such bolt holes may be from four to s'm feet deep in some cases and may be spaced in a pattern about three feet apart. In such rotary drilling, drilling bits, for example, even though made of carbide, may have a relatively short life; they may become so hot as to present a problem where the mine has an inherent ignition hazard; dust created by such rotary drilling may be relatively small and in some cases detrimental to health or conducive to explosive conditions; and drilling time is relatively long.

In embodiments of the instant invention, the foregoing difiiculties have been overcome. Thus, the drilling bits remain relatively cooler and drilling time is relatively shorter. Detritus from impact drilling of this invention tends to be larger in size, although, if desired, provision may be made for collecting dust formed by the bit cutter in the course of impact drilling hereunder. And, holes drilled by the new rotary impact drill tools remain straight and round even though the composition of the rock or other material being drilled is not uniform along the entire length of the hole.

Other objects, features and advantages of this invention will be apparent from the following description, and the accompanying drawings, which are illustrative only, in which FIGURE 1 is a schematic View of a mine roof bolt hole boring machine in operation utilizing one embodiment of this invention;

FIGURE 2 is a view in elevation of the rotary impact drilling tool embodiment shown in FIGURE 1;

FIGURE 3 is a view in axial cross section of the tool embodiment shown in FIGURE 2 taken along line III III of FIGURE 4;

FIGURE 4 is a view in plan, partly in section, taken generally along line IVIV of FIGURE 2;

FIGURE 5 is a view in elevation of the rotor shown in section in FIGURE 3;

FIGURE 6 is a view in section taken along line VI VI of FIGURE 3;

FIGURE 7 is a view in axial cross section taken along line VII--VII of FIGURE 8 of a further rotary impact drilling tool embodiment of this invention; and

FIGURE 8 is a plan view of the tool shown in FIG- URE 7.

Referring to FIGURES 1 to 6, inclusive, of the drawings, there is illustrated therein a powered roof bolt hole drilling machine 10 of conventional nature running on 3,132,792 Patented May 12, 1964 the floor of the mine having a roof 11 to be drilled preliminarily to the insertion in the holes of roof bolts. Machine It) is provided with a transversely movable head 12 and a vertically movable head 13 having a power drive therein connected to a rotary impact drilling tool 14 of this invention to operate a drill bit 15 in an impacting and rotary drilling manner at a suitable speed. The bit 15 extends freely through a steadying bracket 16 which is a part of machine 10. Tool 14 comprises a generally cylindrical casing 17 with an axially extending chamber 18 for an impacting generally cylindrical rotor 19. Casing 17 is provided with circumferential cored passages 21' and a plurality of lateral radially extending bosses 21 with radially extending openings 22 therethrough communicating with chamber 18. Arcuate bearing recesses 23 are provided circumferentially in chamber 18 above and below the openings 22 for arcuate roller bearings 24 having antifriction rollers 25 therein to support rotor 19 laterally against movement while permitting rotor 19 to revolve and to reciprocateaxially for impaction.

An annular closure member 26 is bolted to the top of casing 17 and has a central opening extending close to the cylindrical surface of rotor 19 leaving a narrow space therebetween. Solid ring or Garlock seal means 27 are provided above the upper bearing 24 and comparable sealing means 28 are provided at the other end of the tool to bear against a coupling member 29 keyed to a drive shaft 39 operated by the prime mover for head 13. Antifriction thrust ring bearings 31 are held in place against shoulders in casing 17 by a base plate 33 and around the circumference of coupling 29, being separated by a flange 32 integral with coupling 29. The rotor end of coupling 29 is supplied with a tang receiving recess 34 which is rectangular in plan to receive a tang 35 for rotor 19 which is square in plan. While recess 34 in one dimension is just slightly larger than the corresponding width of tang 35 for ready insertion of the latter through the recess, recess 34 in the other direction at right angles thereto may be longer as illustrated in FIGURE 6 to act as a self-aligning feature in connection with the driving of a chuck 36 at the drill bit end of rotor 19.

Rotor 19 is provided at its bit end with an axially extending socket 37 which is rectangular in plan to receive a rearward square chuck projection 38 which fits in socket 37. A longitudinally drilled opening 39 and cross openings 4t) communicating therewith are intended to assist in circulation of lubricant and provide some space for a change in volume of the lubricant because of a rise in temperature, for example, as the device operates. A circumferential recess 41 which is channel-shaped in cross section extends around the middle of rotor 19 intermediate the respective ends thereof. Recess 41 has a back wall 42, an upper side wall 43 and a lower side wall 44, the orientation terms upper and lower being simply relative since the device may be used vertically as shown or in any other position desired. The sides 43 and 44 flare outwardly and the surface of each is wavy producing an endless sinuous groove as shown in FIGURE 5. Thus, side 43 has alternate cam rises 45 and cam fall portions 46 and side 44 has cam rise portions 47 in alternated relation with cam fall portions 48. The rise portions 45 on one side are in such axial and circumferential relation to cam fall portions 48 on the opposite side of the groove 41 as to, in a preferred mode, subject the sets of thrust members 49 to engage with cam rise portions 45 and the sets of returned members 50 to engagement with cam rise portions 47, respectively and successively, in the course of and while permitting rotation of rotor 19.

Side 43 cooperates with thrust roller guides 49 while side 44 cooperates with return roller guides 50. The respective ends 51 and 52 of the two classes of guides are frusto-conical to suit the radially extending slope of the mi respective sides engaged continuously or substantially continuously by the respective classes of guides. The ends of the guides do not touch the back wall 42 and the slope of the sides and guide ends are selected to maintain the linear speed of rotation at different axial distances along the ends of the respective guides as nearly as possible in correspondence with the linear speeds across the engaged side of groove 41, to promote rolling engagement and minimize friction and wear.

Roller ring bearings 53 are provided in the respective openings 22 in accordance with the respective two sizes of roller guides 49 and '9. The outer end of each radial opening 22 is threaded to receive a threaded plug 54 having spaced wrench holes 55', each plug screwed in a selected distance to adjust the axial projection of a guide into groove 41. Each adjusted plug 54 is held in place by a set screw 56 once the assembly is completed. Thrust ball bearings 57 fit an outwardly necked portion of each guide and bear against the inner face of the respective plugs 54? so that each guide is mounted for rotation only in its adjusted position in its respective opening 22. The difference in size of the respective guides 2-? and 59 reflects the greater force which has to be exerted by the thrust guides 49, as each rise =35 encounters ends 51 of guides d3; whereas a lesser force is needed for the return axial stroke of rotor 19 as the ends 52 of guides St) encounter the rise portions 437. Home as shaft 30 rotates, rotor 19 is revolved and while revolving, reciprocates alternately moving through its axial impacting stroke toward the bit end of the device and its axial return stroke toward the drive or coupling end of the device ltd. In the particular embodiment under discussion, there are thrust roller guides 49 spaced 90 from one another in the two positions shown in FIGURE 4- and within the two further bosses ZIT, while there are return guides 50 in the position shown and in the openings of the two bosses 21R, reflecting the difference in force between an impact thrust portion of the rotor impact rotation and a return portion, the amplitude of the reciprocation being relatively small so that end Sll preferably never touches side 44 and, conversely, end 52 preferably never touches ide 43 of groove 41.

As shown in FIGURE 4, one of the eight boss positions around the out-side of casing 17 is occupied by an axially extending trough 5% closed by a plate 59 to form an oil well or reservoir which communicates by means of a passage as with chamber 38, passages 3'3 and 36 and the various antifriction bearings, the cored passages 24) and the openings 22 inside of the plugs 54. The respective roller guides may also be provided with axially drilled openings 62 for lubrication access and circulation. When assembly id is made, but before it is attached to power unit 13 by bolts 63, it may be filled with oil through an opening dd communicating with the lowermost passage 20 and normally closed by a pipe plug 65. Further, if desired, the uppermost passage 29 illustrated in FIGURE 3 may be provided with a normally closed spring-loaded pressure relief valve where the device 14 is to be used under relatively more severe service conditions. Instead of oil, the lubricant may also be a relatively lightweight grease which will seek to provide its own level (high slump grease).

Chuck 36 in the form illustrated is suitable for use as a rotary impact drilling tool chuck alone, or in combination with dust collection equipment. As shown, chuck 36 is round in plan and has an axially extending bit or drilling tool recess 66 with an axial opening through the bottom thereof communicating with cross passages 67 extending out through the sides of the chuck to discharge dust particles into a continuous cylindrical inlet opening 63 in a suction ring fitting 69 which is tubular in cross section and provided with an outlet 7@ on the outside thereof into a hose fitting connection ill with a flexible hose '72 clamped thereto. The ring 6% is connected to a vacuum dust cleaning and collector device, therefore inhibiting escape of any deleterious dust created in the cutting by -a rotary impact drilling operation of device 14. Fitting 6? is provided with a cylindrical flange 73 which fits around cap 26 and is removably bolted thereto. An internal flange 74 on fitting 69 covers the space between rotor 19 and the edge of the central opening of closure 25, a felt ring seal 75 being provided to bear against the rotor surface if desired. Further, a ring seal 76 may be carried by chuck 3d and bear against the inner vertical cylindrical side of ring fitting 6% above its opening 68. Additionally in the illustrated embodiment, a flange 77 extends annular outwardly of chuck 36 above seal '76 and the cylindrical space between ring 69' and chuck 36 to fling ofi and disperse any particles falling down alongside the chuck which otherwise might try to find their was. between the rotating and non-rotating parts.

The bit recess 66 is square in plan and engages the lower end, in the illustration, of a square tubular shank '78, the upper end of which holds the tang of a hollow drilling bit 79 with internal passages 80 leading to the inside of the shank through which air is drawn in the direction indicated by the arrow 81 in connection with the collection of dust therethrough. On the other hand, whether or not fitting 69 is taken off, a solid bit with a long solid shank may be used instead for impact drilling when the tool 14 is operated, obtaining advantages hereinabove described. If desired, further, chuck 36 may be provided with a hole 82 through opposite sides of recess as so that a pin may be passed therethrough to join shank 78 positively to chuck 36 and similarly bit 79 may be connected to shank 78 so that after a hole is drilled by tool 14, when the bit is pulled out of the hole, neither it nor any shank used will separate from tool 14. Normally no such pin or set screw connection is needed when the bolt holes are drilled generally vertically above the tool 14 because the drilled holes are made so true by means of this invention that the withdrawal of the bit and shank takes place under the force of gravity when tool 14 is lowered without tending to stick in the hole or otherwise become separated from the tool.

A further embodiment of this invention is illustrated in FIGURES 7'and 8, wherein parts corresponding generally in structure and function to parts in the embodiment of FIGURES 2 to 6, inclusive, are provided with the same reference numerals, respectively, with the addition of a prime accent thereto. The embodiment of FIG- URES 7 and 8, as illustrated, does not include any dust collection feature. Chuck 36' is provided with an integral annular flange till) which covers the cylindrical space ltll at the top of cap 26' adjacent the outer surface of rotor 19. Further, double-tiered ring seal 27' has its interior above its lower tier in communication with a passage ltll, the outer end of which is closed by a grease fitting N3. Periodically, grease may be forced into and through fitting 1433 and passage 102 to enter the space between the two seal tiers and exit through space 101 and annular space 194 thereby both lubricating and preventing entry of dirt and foreign particles into chamber 18' and the parts associated therewith in tool 14'. The internal lubricatable space between upper seal 27' and lower seal 28 may be lubricated by means of oil in well 60' which well is filled through an opening at the top normally closed by a threaded stopper or such'lubrication may be performed by means of a lightweight grease forced through. a lubricant fitting 10-6 communicating with lower cored space 20 and the other spaces and passages in communication with chamber 18'. Where a grease, as distinguished from an oil, is used, it is usually desirable to have such grease one which will be self-leveling. It will also be noted that reservoir 6%) may be provided with relatively large passages 197 to bearings 24' and chamber 18'.

In tool 14, any excess pressure exerted by lubricant may be relieved through a venting port 117, controlled by a spring-loaded ball check 118 which normally closes off communication between the port and the lubricated interior spaces of the tool unless and until the predetermined pressure setting of the check 118 is exceeded.

Socket 37' in the embodiment of FIGURES 7 and 8 is circular and threaded to receive a circular threaded tang 38' which joins rotor and chuck together. The upper end of socket 37' is a circular unthreaded counterbore 37'a which fits around the body of chuck 36' below flange 100. When a drill bit with a square tang or drill bit shank with a square lower end, is seated in bit recess 66', the rotation md' reciprocation of rotor 19' in the course of operation will correspondingly rotate the drill bit and in the stroke toward the cutting end of the bit will also provide an impact for advantageous and relatively rapid drilling even in very hard rock at a speed, for example, of about 300 rpm. If desired, a threaded hole 168 is provided in the side of chuck 36 for a set screw in the event that it is desired to positively afiix the chuck to a drill bit or drill shank, rather than having the two merely operatively connected by the seating of the bit member or shank in recess 66' when tool 14' is used vertically, as shown in FIGURE 7. Such a set screw or other positive connection would normally be used when tool 14' is used in some other position.

Still further, in embodiment 14', the rearwardly projecting tang portion 35 of rotor 19' is in the form of a separate block, the upper part of which is threadably connected to a counterbored and tapped enlarged portion 39'a of passage 39, the block being held in position by a press fit locking pin 109 engaging both block 35 and the body of rotor 19, as shown. Base plate 33 is bolted to casing 17' and also to an adapter plate 110 which fits an opening 111 in a housing 112 which encloses a power take-E from some prime mover source (not shown) which is capable, when actuated, of driving rotor 19' through a sprocket chain 113. Chain 113 engages and drives a driven sprocket 114 having an upwardly extending hub 115 which is keyed to coupling 29' which engages and drives tang 35' to cause rotor 19' to revolve and reciprocate at the same time for impact rotor drilling. A bolt 116 is also used to join sprocket Wheel 114 and connector 29'. Thrust bearings 31' are utilized in adapter plate 110 and housing 112 to fix the position of sprocket 114 and tool 14' relative to housing 112.

After drilling bolt holes for roof bolts in mines, tools of this invention may also be left in place in a roof bolt hole drilling machine and utilized to place the roof bolts and turn a socket wrench to expand the expansion nut after the roof bolts are in place in the bolt holes, and thereby cause the roof bolts to take hold and engage in their roof supporting function. Tools of this invention are susceptible of many other uses and forms, e.g., including ones in which friction hearings or members are substituted for antifriction ones, or ones in which the tang and socket members are reversed. Various other changes may be made in the illustrated embodiments herein and other embodiments provided without departing from the spirit of our invention or the scope of the appended claims.

We claim:

1. A rotary impact drilling tool comprising, in combination, a casing having an axially extending chamber, a cylindrical axially reciprocable rotor, drive means to rotate said rotor and permit it to move axially to a predetermined extent, antifriction roller bearings positioned in said chamber for mounting said rotor to permit it to revolve around its axis and to move axially relative thereto, said bearings having the axes of their rollers parallel to the axis of said chamber and rotor, said rotor having a circumferential recess around the center thereof, said recess being channel-shaped in cross section with the sides of said channel flaring toward the outside of said rotor, each side of said recess being wavy in axially corresponding fashion to provide a pair of continuously sinuous sides to cause and control the reciprocable axial movement of said rotor, a plurality of radially extending openings through and around said casing substantially opposite said recess, a respective plurality of thrust and return roller guides having their respective roller axes normal to the axis of said chamber and rotor, said guides having inner frusto-conical ends projecting into said recess and terminating adjacent but spaced from the back wall of said recess, said thrust guides having their respective ends in engagement only with the side of said recess toward the drill bit end of said rotor, said return guides having their respective ends in engagement only with the side of said recess toward the drive end of said rotor, closures for the outer ends of said radial openings, means for preventing outward movement of said guides, means for lubricating said rotor, bearings and guides, and means for sealing the interior of said chamber against entry of dirt and escape of lubricant.

2. A rotary impact drilling tool comprising, in combination, a casing having an axially extending chamber, a cylindrical axially reciprocable rotor positioned in said chamber to permit said rotor torevolve around its axis and to move axially to a predetermined extent, means to rotate said rotor and permit it to move axially, said rotor having a circumferentially endless sinuous groove around the middle thereof, said groove being channel-shaped in cross section with the sides of said channel flaring somewhat toward the outside of said rotor to control respectively the reciprocable axial strokes of said rotor, a respective plurality of thrust and return roller guides positioned in said casing substantially opposite said groove, said guides having their respective roller axes intersecting the axis of said chamber and rotor, said guides having inward frustoconical ends projecting inwardly into said groove and terminating adjacent the back wall of said groove, said thrust guides having their respective ends engageable substantially continuously only by the side of said groove toward the drill bit end of said rotor, said return guides having their respective ends engageable substantially continuously only by the side of said groove toward the drive end of said rotor, and means for preventing axially outward movement of said guides.

3. A rotary impact drilling tool as set forth in claim 2, having, an axially extending tang for said rotor at its drive end, a coupling block having a tang receiving recess for said tang, said coupling block being mounted in frictionless thrust bearings for rotation only, the axial length of said tang receiving recess exceeding the length of the axial reciprocating stroke of said rotor, and driving means to rotate said coupling to cause said rotor to move with axial reciprocation in the course of its rotation.

4. A rotary impact drilling tool as set forth in claim 2, in which, said rotor is provided with an axially recessed socket, a cylindrical chuck having a rearwardly extending portion to fit said socket for rotation and axial reciprocation of said chuck with said rotor, said chuck having an axial drill bit recess on the bit side thereof and lateral passageways therein communicating with said bit recess, a suction ring having an annular inlet surrounding the outer ends of said passageways, said ring having a suction dust collection outlet, and shielding means extending across the space between said chuck and said ring, whereby when a hollow bit is connected to said bit recess dust created at the drill bit edges will be drawn through said recess and passageways into said ring and out through said collector outlet to a dust collector.

5. A rotary drilling tool as set forth in claim 2, having, an annular closure for said casing surrounding the upper portion of said rotor, annular sealing means extending between said closure and rotor, means for flushing out said annular sealing means out through the space between said closure and rotor, and an annular rotatable flange connected to said closure and overlying said space to shield it against entry of foreign particles.

6. A rotary impact drilling tool as set forth in claim 2,

i in which, roller bearings circumferentially line said chamber to engage said rotor for antifriction rotation free of movement normal to the axis of said roller, said roller bearings having the axes of their rollers parallel to the axis of said rotor to accommodate said predetermined axial movement of said rotor, antifriction bearings for said respective roller guides around the circumference thereof, and antifriction thrust bearings adjacent the outer end of said roller guides for said roller guides.

7. A rotary impact drilling tool as set forth in claim 6, in which, a well for a self-leveling lubricant is provided, said casing and rotor having passages for lubrication of said rotor in communication with said well, roller guides and bearings by means of said lubricant.

8. A rotary impact drilling tool as set forth in claim 7, in which, said well extends axially along said casing between two of said roller guides.

9. A rotary impact drilling tool having a drive end and a working end, comprising, in combination, an axially extending chamber, an axially reciproeable rotor positioned in said chamber, drive means positioned in said drive end to rotate said rotor and permit axial movement thereof relative to said drive means, said rotor having a peripherally endless cam groove with sides toward the respective ends of said rotor, a plurality of cam rise and cam fall portions along at least the side of said cam groove toward said working end, and a plurality of inwardly extending thrust and return guides having their respective axes intersecting the axis of said rotor, at least said respective thrust guides having their respective inward ends substantially continuously in engagement with the side of said cam groove toward said working end.

10. A rotary impact drilling tool as set forth in claim 9, having,'a drill bit chuck operatively connectable to said rotor, said chuck having dust collection passages extending laterally therethrough, and a suction chamber surrounding said chuck with an inlet opposite said lateral passages and a dust collection outlet adapted to be subjected to suction.

References Cited in the file of this patent UNITED STATES PATENTS 1,899,438 Grant Feb. 28, 1933 2,327,497 Burch et al Aug. 24, 1943 2,353,321 Snodgrass July 11, 1944 2,879,035 Tilden Mar. 24, 1959 2,970,483 Schrum Feb. 7, 1961 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No 3 132 702 May 12 1964 Wilbur Tc. Schrum Srn 9 et al.

It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 2,, line 65,

for "engage" read engagement line wh for "returned" read return column 6 line 64 for "drill" read drilling line 67 after "rotary" insert impact Signed and sealed this 22nd day of September 1964.

(SEAL) Attest:

ERNEST W. SWIDER' EDWARD J. BRENNER Attesting Officer Commissioner of Patents 

9. A ROTARY IMPACT DRILLING TOOL HAVING A DRIVE END AND A WORKING END, COMPRISING, IN COMBINATION, AN AXIALLY EXTENDING CHAMBER, AN AXIALLY RECIPROCABLE ROTOR POSITIONED IN SAID CHAMBER, DRIVE MEANS POSITIONED IN SAID DRIVE END TO ROTATE SAID ROTOR AND PERMIT AXIAL MOVEMENT THEREOF RELATIVE TO SAID DRIVE MEANS, SAID ROTOR HAVING A PERIPHERALLY ENDLESS CAM GROOVE WITH SIDES TOWARD THE RESPECTIVE ENDS OF SAID ROTOR, A PLURALITY OF CAM RISE AND CAM FALL PORTIONS ALONG AT LEAST THE SIDE OF SAID CAM GROOVE TOWARD SAID WORKING END, AND A PLURALITY OF INWARDLY EXTENDING THRUST AND RETURN GUIDES HAVING THEIR RESPECTIVE AXES INTERSECTING THE AXIS OF SAID ROTOR, AT LEAST SAID RESPECTIVE THRUST GUIDES HAVING THEIR RESPECTIVE INWARD ENDS SUBSTANTIALLY CONTINUOUSLY IN ENGAGEMENT WITH THE SIDE OF SAID CAM GROOVE TOWARD SAID WORKING END. 